1 Ganglia-groups of neuron cell bodies that lie peripheral to the central nervous system in vertebrates. 2  Bipolar neurons-cell body located near the middle of the axon; characteristic of retinal neurons. 3  Unipolar neurons-cell body lies off to one side of axon; characteristic of sensory neurons.
The principal host for diamonds are rocks formed in the earth's mantle that are known as eclogite and peridotite that are carried to the earth's surface in magmas known as kimberlit e and lamproite.
Gems Formed in the Earthâs Mantle. Knowledge of the earthâs mantle is still rather limited. However, the evidence shows that some gems actually form in the mantle. To do so, they need to crystallize at an extremely high temperature. The most notable examples of gems formed in the earthâs mantle are diamond and peridot. By studying the peridot deposits in Arizona, geologists now believe they were created on rocks floating in the mantle, approximately 20 to 55 miles below the surface. An explosive eruption brought them near the surface of the earth.